1. Field of the Invention
This invention relates to stents and is directed more particularly to a self-expanding, generally cylindrical stent which is repositionable after being set in place.
2. Brief Description of the Prior Art
Self-expanding stents are generally known in the art. U.S. Pat. No. 4,580,568, issued Apr. 8, 1986, to Cesare Gianturco, discloses an endovascular stent formed of stainless steel wire. The stent is compressed into a reduced size having an outer diameter substantially smaller than the stent in its expanded shape. The stent is held in its compressed state during its passage through a small bore catheter until delivered into a vascular system passageway, whereupon the stress in the stent causes the stent to expand in the larger bore vascular passageway to hold open the passageway. When the stent is compressed, the bends in the wire, which is of a zig-zag configuration, store stress, and the stent is expandable by the release of the stress stored in the bends. Once set in place, the radial extremities of the stent bear against the inside walls of the passageway. There is no ready means by which the stent may be again compressed, or softened, so that the stent may be repositioned.
It would be beneficial to the medical arts to have available a stent adapted for compression into a small size to facilitate introduction into a vascular passageway, and adapted for self-expansion in the vascular passageway to hold open the passageway, and also adapted to be softened and/or contracted to permit repositioning of the stent.